Autonomic ganglia typically contain not only neurons and their processes, but also a scattering of small cathecholamine-containing cells called SIF cells (small intensely fluorescent cells), interneurons, paraganglion cells, etc. The function of these small cells is unknown, but their widespread distribution suggests that they may be important--serving, perhaps, to modulate the growth and excitability of the nervous system. The purpose of the proposed research is to study the morphology of catecholamine secretion from these cells following drug and nerve stimulation, and to extend our knowledge about their structure, chemistry, and relationships to the nervous system.